Aromatic carbonate resins such as polycarbonate resins are thermoplastic resinous materials possessing many excellent physical and chemical properties which render them useful in a wide range of applications. They exhibit, for example, excellent properties of toughness, impact resistance, heat resistance and dimensional stability, optical clarity or non-opaqueness, and physiological inertness. Because of their excellent property spectrum, polycarbonate resins are used in various utilities including various molded and extruded articles. The polyphenylene ethers are also a well known group of polymers. These polymers are characterized by good thermal characteristics and good hydrolytic stability. For many years, researchers have attempted to wed the good characteristics of both polycarbonates and polyphenylene ethers by blending them in many different ways, preparing copolymers or adding miscibilizing agents. These efforst have met with little success. Generally, the problem that arises when the two polymers are admixed is that the melt state becomes unstable. This problem manifests itself in the admixture of the two polymers by an observed brittleness that makes it difficult to mold pieces therefrom and low impact strengths accompanied by brittle break when such articles can be molded.
It has now been discovered that such blends of aromatic polycarbonate and polyphenylene ether can be prepared with desirable properties when a graft modification polyphenylene ether is employed. The graft modification occurs through the chemical reaction of the polyphenylene ether with an aliphatic unsaturated dicarboxylic acid, dicarboxylic acid precursor or a carboxylic acid ester precursor.
This new composition provides a spectrum of benefits which depends upon the quantity of the aromatic polycarbonate or the polyphenylene ether. Impact modifiers may be added for increased impact resistance and ductility of the composition. It is believed that some covalent bonding between the polycarbonate and the graft modified polyphenylene ether can possibly occur during processing.